Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Carolinas/Richmond Carolinas Richmond [Member] Carolinas Richmond [Member] Chicago/Minneapolis Chicago Minneapolis [Member] The Company's reportable segment of Chicago/Minneapolis. Cincinnati/Columbus/Indianapolis Cincinnati/Columbus/Indianapolis [Member] Cincinnati/Columbus/Indianapolis [Member] Dallas Dallas [Member] Dallas reportable segment Florida Florida [Member] Area in the state of Florida which formally included the segments Tampa, Orlando and South Florida. Houston Houston [Member] Houston Reportable Segment Lehigh/Central PA Lehigh Central PA [Member] Lehigh Central PA [Member] Philadelphia Philadelphia [Member] Philadelphia [Member] Southern California Southern California [Member] Operating segment of the company for the properties located in Southern California. United Kingdom United Kingdom [Member] United Kingdom Member. Other Other Segments [Member] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Development service fee income Development Service Fee Income [Member] Development Service Fee Income [Member] Discontinued operations Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Intersegment Eliminations Intersegment Eliminations [Member] Operating Segments Operating Segments [Member] Segment Reconciling Items Segment Reconciling Items [Member] Corporate, Non-Segment Corporate, Non-Segment [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] North America North America [Member] United Kingdom UNITED KINGDOM Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenue Revenues Net operating income Operating Income (Loss) Interest expense Interest Expense Depreciation and amortization expense Depreciation, Depletion and Amortization, Nonproduction Gain on property dispositions Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Equity in earnings of unconsolidated joint ventures Income (Loss) from Equity Method Investments General and administrative expense General and Administrative Expense Leasing cost Lease, Cost Other operating expense Other Cost and Expense, Operating Discontinued operations excluding (loss) gain on property dispositions Disposal Group, Including Discontinued Operation, Operating Income (Loss) Income taxes Income Tax Expense (Benefit) Other Other Nonoperating Income (Expense) Income from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Liabilities Other Liabilities [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap Interest Rate Swap [Member] Interest Rate Lock Commitments Interest Rate Lock Commitments [Member] Interest Rate Lock Agreement A Interest Rate Lock Agreement A [Member] Interest Rate Lock Agreement A [Member] Interest Rate Lock Agreement B Interest Rate Lock Agreement B [Member] Interest Rate Lock Agreement B [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Interest Expense Interest Expense [Member] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Other Comprehensive Income (Loss) Other Comprehensive Income (Loss) [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash Flow Hedging Cash Flow Hedging [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Amount of gain related to the effective portion recognized in other comprehensive (loss) income Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Amount of loss related to the effective portion subsequently reclassified to interest expense Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion Total Amount of Interest Expense Presented in the Consolidated Statements of Comprehensive Income Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness Interest Rate Derivatives [Abstract] Interest Rate Derivatives [Abstract] Number of interest rate swaps Number of Interest Rate Derivatives Held Aggregate notional amount Derivative, Notional Amount Derivative, gain on derivative Derivative, Gain on Derivative Number of derivative instruments expired Derivative, Number of Instruments Expired Derivative, Number of Instruments Expired Gain (loss) on contract termination Gain (Loss) on Contract Termination Fair value Derivative Liability Reclassification during next 12 months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Termination value Assets Needed for Immediate Settlement, Aggregate Fair Value Schedule of operating information by reportable segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of total assets by reportable segments Reconciliation of Assets from Segment to Consolidated [Table Text Block] Cash and Cash Equivalents [Abstract] Cash and Cash Equivalents, at Carrying Value [Abstract] Cash and Cash Equivalents, at Carrying Value [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents Cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Equity Method Investee Equity Method Investee [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Liberty Property 18th & Arch Liberty Property 18th & Arch [Member] Liberty Property 18th & Arch includes both joint ventures that own the Comcast Innovation and Technology Center in Philadelphia Pennsylvania. Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Construction in Progress Construction in Progress [Member] Building and Building Improvements Building and Building Improvements [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Guarantee Obligations Guarantee Obligations [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Number of equity method investments (in investments) Number of equity method investments Number of equity method investments Number of stories in a high-rise building (in stories) Number of stories in a high-rise building Number of stories in a high-rise building Number of hotel rooms (in rooms) Number of hotel rooms Number of hotel rooms in a hotel Leaseable square feet (in sqft) Net Rentable Area Loss contingency accrual Loss Contingency Accrual Anticipated Aggregate Investment Anticipated Aggregate Investment Total anticipated cost of investment in assets including but not limited to assets under construction. Investments in and advances to unconsolidated joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Ownership percentage of equity method investment Equity Method Investment, Ownership Percentage Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Liberty Property Limited Partnership Liberty Property Limited Partnership [Member] Limited Partnership. Statement [Line Items] Statement [Line Items] ASSETS Assets [Abstract] Real estate: Real Estate [Abstract] Land and land improvements Land and Land Improvements Building and improvements Investment Building and Building Improvements Less accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Operating real estate Real Estate Investments, Other Development in progress Development in Process Land held for development Land Available for Development Net real estate Real Estate Investment Property, Net Cash and cash equivalents Restricted cash Accounts receivable Accounts Receivable, Net Deferred rent receivable Deferred Rent Receivables, Net Deferred financing and leasing costs, net of accumulated amortization (March 31, 2019, $175,126; December 31, 2018, $165,786) Deferred Costs, Leasing, Net Assets held for sale Disposal Group, Including Discontinued Operation, Assets Right of use asset Operating Lease, Right-of-Use Asset Prepaid expenses and other assets Prepaid Expense and Other Assets Total assets Assets LIABILITIES Liabilities [Abstract] Mortgage loans, net Secured Debt Unsecured notes, net Unsecured Debt Credit facilities Long-term Line of Credit Accounts payable Accounts Payable Accrued interest Interest Payable Dividend and distributions payable Dividends Payable Lease liabilities Operating Lease, Liability Other liabilities Other Liabilities Liabilities held for sale Disposal Group, Including Discontinued Operation, Liabilities Total liabilities Liabilities Noncontrolling interest - operating partnership - 213,483 and 301,483 preferred units outstanding as of March 31, 2019 and December 31, 2018, respectively Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests EQUITY Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common shares of beneficial interest, $.001 par value, 283,987,000 shares authorized; 148,258,042 and 147,899,354 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively Common Stock, Value, Issued General partner’s equity - 148,258,042 and 147,899,354 common units outstanding as of March 31, 2019 and December 31, 2018, respectively General Partners' Capital Account Limited partners’ equity – 3,520,205 common units outstanding as of March 31, 2019 and December 31, 2018 Limited Partners' Capital Account Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Distributions in excess of net income Accumulated Distributions in Excess of Net Income Total Liberty Property Trust shareholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interest - operating partnership Stockholders' Equity Attributable to Noncontrolling Interest [Abstract] Noncontrolling interest – operating partnership - 3,520,205 common units outstanding as of March 31, 2019 and December 31, 2018 Noncontrolling Interest in Operating Partnerships Noncontrolling interest – consolidated joint ventures Noncontrolling Interest in Joint Ventures Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities, noncontrolling interest - operating partnership and equity Liabilities and Equity Commitments and Contingencies Disclosure [Abstract] Number of legal claims Loss Contingency, Pending Claims, Number Statement of Cash Flows [Abstract] OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Amortization of deferred financing costs Amortization of Debt Issuance Costs Expensed pursuit costs Other General and Administrative Expense Impairment charges - real estate assets Impairment of real estate, including discontinued operations Impairment of real estate concept including amounts allocated to discontinued operations Equity in earnings of unconsolidated joint ventures Gain on property dispositions Gain (Loss) on Sale of Properties Share-based compensation Share-based Compensation Development service fee accrual Increase (Decrease in Other Operating Liabilities Development Service Fee Amount of increase (decrease) in operating liabilities classified as development service fee. Other Other Operating Activities, Cash Flow Statement Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Deferred rent receivable Straight Line Rent Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued interest Increase (Decrease) in Interest Payable, Net Other liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities [Abstract] Investment in properties – acquisitions Payments to Acquire Buildings Investment in properties – other Payments for Capital Improvements Investments in and advances to unconsolidated joint ventures Payments to Acquire Equity Method Investments Distributions from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution, Return of Capital Net proceeds from disposition of properties/land Proceeds from Sale of Real Estate Held-for-investment Investment in development in progress Payments to Develop Real Estate Assets Investment in land held for development Payments To Acquire And Develop Land The cash outflow associated with the purchase of or development of land held for investment. Payment of deferred leasing costs Payments for Leasing Costs Release of escrows and other Increase (Decrease) in Deposit Assets Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Investing Activities FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities [Abstract] Net proceeds from issuance of common shares Proceeds from Issuance of Common Stock Share repurchases, including shares related to tax withholdings Payments for Repurchase of Common Stock Redemption of preferred units Payments for Repurchase of Redeemable Preferred Stock Proceeds from unsecured notes Proceeds from Issuance of Unsecured Debt Repayments of mortgage loans Repayments of Secured Debt Proceeds from credit facility Proceeds from Long-term Lines of Credit Repayments on credit facility Repayments of Long-term Lines of Credit Payment of deferred financing costs Payments of Financing Costs Distribution paid on common shares Payments of Ordinary Dividends, Common Stock Capital contributions Proceeds from Contributed Capital Distributions to partners/noncontrolling interests Payments of Ordinary Dividends, Noncontrolling Interest Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net increase in cash, cash equivalents and restricted cash Cash and Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Increase in cash, cash equivalents and restricted cash related to foreign currency translation Effect of Exchange Rate on Cash and Cash Equivalents Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash at end of period Temporary Equity Disclosure [Abstract] Temporary Equity, by Class of Stock [Table] Temporary Equity, by Class of Stock [Table] Temporary Equity [Line Items] Temporary Equity [Line Items] Noncontrolling Interest - Operating Partnership/Limited Partnership/Limited Partners' Equity - Preferred Units Stockholders' Equity Note Disclosure [Text Block] Earnings Per Share [Abstract] Schedule of Earnings Per Share, Basic and Diluted [Table] Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Earnings Per Unit, Basic and Diluted [Line Items] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Schedule of earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Units Common Class B [Member] Income (Numerator) [Abstract] Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Income from continuing operations net of noncontrolling interest - consolidated joint ventures Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Income from continuing operations available to common unitholders Income from Continuing Operations available to Common Unitholders Income from Continuing Operations available to Common Unitholders Income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Net income available to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Weighted Average Units (Denominator) [Abstract] Weighted Average Number of Shares Outstanding, Diluted [Abstract] Income from continuing operations net of noncontrolling interest - basic, weighted average shares (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive units for long-term compensation plans Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Income from continuing operations net of noncontrolling interest - diluted, weighted average shares (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings Per Unit, Basic [Abstract] Earnings Per Share, Basic [Abstract] Income from continuing operations (in usd per share) Income (Loss) from Continuing Operations, Per Basic Share Income from discontinued operations (in usd per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Income per common share or unit - basic (in usd per share) Earnings Per Share, Basic Earnings Per Unit, Diluted [Abstract] Earnings Per Share, Diluted [Abstract] Income from continuing operations (in usd per share) Income (Loss) from Continuing Operations, Per Diluted Share Income from discontinued operations (in usd per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Income per common share or unit - diluted (in usd per share) Earnings Per Share, Diluted Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Attributable to Noncontrolling Interest AOCI Attributable to Noncontrolling Interest [Member] AOCI Attributable to Parent AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Beginning balance Unrealized income (loss) Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Reclassification adjustment Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Ending balance Total accumulated other comprehensive loss Total accumulated other comprehensive loss included in shareholders' equity/owners' equity Common shares Common Class A [Member] Earnings Per Share, Basic and Diluted [Line Items] Income from continuing operations net of noncontrolling interest Income from discontinued operations net of noncontrolling interest Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Net income available to common shareholders Weighted Average Shares (Denominator) [Abstract] Dilutive shares for long-term compensation plans, weighted average shares (in shares) Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of future minimum rent payments Lessee, Operating Lease, Liability, Maturity [Table Text Block] Future minimum rental payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of lease income Lease, Cost [Table Text Block] Schedule of lease payments receivable Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block] Redeemable Noncontrolling Interest, by Legal Entity [Table] Redeemable Noncontrolling Interest, by Legal Entity [Table] Redeemable Noncontrolling Interest [Line Items] Redeemable Noncontrolling Interest [Line Items] Limited Partners' common units outstanding Limited Partners' Capital Account, Units Outstanding Market value of common units based on closing price Redeemable Noncontrolling Interest, Equity, Common, Fair Value Income Statement [Abstract] REVENUE Revenues [Abstract] Rental revenue Operating Lease, Lease Income Development service fee income Revenue from Contract with Customer, Including Assessed Tax Total revenue EXPENSES Operating Expenses [Abstract] Rental property Direct Costs of Leased and Rented Property or Equipment Real estate taxes Real Estate Tax Expense General and administrative Leasing expense Interest expense Depreciation and amortization Development service fee expense Cost of Goods and Services Sold Impairment charges - real estate assets Impairment of Real Estate Total expenses Costs and Expenses OTHER INCOME (EXPENSE) Nonoperating Income (Expense) [Abstract] Interest and other income Interest and Other Income Gain on property dispositions Income from continuing operations before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income from continuing operations Discontinued operations (including gain on sale net of impairments of $8.7 million on property dispositions for the three months ended March 31, 2019 and $90.0 million for the three months ended March 31, 2018) Net income Noncontrolling interest – operating partnership Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable Noncontrolling interest – consolidated joint ventures Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Nonredeemable Comprehensive income attributable to common shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Other comprehensive income - foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other comprehensive (loss) income - derivative instruments Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to noncontrolling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to common shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Earnings per common share or unit Basic: Income per common share or unit - basic (in usd per share) Diluted: Income per common share or unit - diluted (in usd per share) Weighted average number of common shares or units outstanding Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic (in shares) Diluted (in shares) Net income allocated to general partners Net Income (Loss) Allocated to General Partners Net income allocated to limited partners Net Income (Loss) Allocated to Limited Partners Amounts attributable to common shareholders or unitholders Income Amounts Attributable to Parent, Disclosures [Abstract] Income from continuing operations Income from discontinued operations Net income available to common shareholders or unitholders Income per Common Share of the Trust Earnings Per Share [Text Block] Unconsolidated Joint Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Noncontrolling Interests of the Trust Noncontrolling Interest Disclosure [Text Block] Discontinued Operations and Disposal Groups [Abstract] Schedule of disposal groups Disposal Groups, Including Discontinued Operations [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock Option Exercises [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock Option Employee Stock Option [Member] Stock Option Exercises [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Amount of options exercised in period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Schedule of Antidilutive Options Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive options excluded from computation of earnings per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Property, Plant and Equipment [Abstract] Impairment and Disposal of Long-Lived Assets Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Debt Instrument, Fair Value Disclosure [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Mortgage Loans Mortgages [Member] Unsecured Notes Unsecured Debt [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long term debt Long-term Debt, Fair Value Document and Entity Information [Abstract] Document And Entity Information. Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Organization and Basis of Presentation Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Not Discontinued Operations Disposal Group, Not Discontinued Operations [Member] Atlanta Atlanta [Member] Atlanta [Member] New Jersey New Jersey [Member] New Jersey business segment [Member] DC Metro DC Metro [Member] DC Metro reportable segment. Acres of Developable Land Land and Land Improvements [Member] Land, Buildings and Improvements Land, Buildings and Improvements [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Number of buildings (in buildings) Number of Real Estate Properties Acres of Developable Land (in acres) Area of Land Leaseable Square Feet (in sqft) Purchase Price (in thousands) Property, Plant and Equipment, Additions Gross Proceeds (in thousands) Property, Plant and Equipment, Disposals Share Repurchase [Abstract] Share Repurchase [Abstract] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] 2017 Share Repurchase Program 2017 Share Repurchase Program [Member] 2017 Share Repurchase Program [Member] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Share repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Stock repurchased in period (in shares) Stock Repurchased During Period, Shares Assets Held for Sale [Abstract] Assets Held for Sale [Abstract] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Included in Continuing Operations Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Included in Discontinued Operations Discontinued Operations, Held-for-sale [Member] Total Held for Sale, Includes Disposal Groups and Discontinued Operations [Member] Includes all assets held for sale as of the end of the period. This includes both discontinued operations and not discontinued operations. Balance Sheet Disclosures by Disposal Groups [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract] Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract] Land and land improvements Disposal Group, Including Discontinued Operations, Land and Land Improvements Disposal Group, Including Discontinued Operations, Land and Land Improvements Buildings and improvements Disposal Group, Including Discontinued Operations, Building and Improvements Disposal Group, Including Discontinued Operations, Building and Improvements Land held for development Disposal Group, Including Discontinued Operation, Land Available for Development Land available for development that is included in a disposal group or assets held for sale. Accumulated depreciation Disposal Group, Including Discontinued Operations, Accumulated Depreciation Disposal Group, Including Discontinued Operations, Accumulated Depreciation Deferred financing and leasing costs, net Disposal Group, Including Discontinued Operation, Intangible Assets Other assets Disposal Group, Including Discontinued Operation, Other Assets Total assets held for sale Schedule of operating properties and land parcels Property, Plant and Equipment [Table Text Block] Gain on property dispositions in discontinued operations Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Schedule of preferred units Temporary Equity [Table Text Block] Impairment Charges [Abstract] Impairment Charges [Abstract] Schedule of Impaired Long-Lived Assets Held and Used [Table] Schedule of Impaired Long-Lived Assets Held and Used [Table] Impaired Long-Lived Assets Held and Used by Type [Axis] Impaired Long-Lived Assets Held and Used by Type [Axis] Impaired Long-Lived Assets Held and Used, Asset Name [Domain] Impaired Long-Lived Assets Held and Used, Asset Name [Domain] Office Building Office Building [Member] Land Land [Member] Impaired Long-Lived Assets Held and Used [Line Items] Impaired Long-Lived Assets Held and Used [Line Items] Impairment charges Asset Impairment Charges Valuation adjustment Real Estate Owned, Valuation Allowance Series I-2 Redeemable Preferred Stock [Member] Deferred financing and leasing costs, accumulated amortization Deferred Costs, Leasing, Accumulated Amortization Noncontrolling interest - operating partnership, preferred units outstanding Temporary Equity, Shares Outstanding Common shares of beneficial interest, par value per share Common Stock, Par or Stated Value Per Share Common shares of beneficial interest, shares authorized Common Stock, Shares Authorized Common shares of beneficial interest, shares issued Common Stock, Shares, Issued Common shares of beneficial interest, shares outstanding Common Stock, Shares, Outstanding Schedule of gains or losses recognized related to derivatives Derivative Instruments, Gain (Loss) [Table Text Block] Schedule of derivative instruments, classification on the accompanying balance sheets Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Limited Partners' Equity of the Operating Partnership [Abstract] Limited Partners' Equity of the Operating Partnership [Abstract] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Market value of common units based on closing price Debt Disclosure [Abstract] Indebtedness Debt Disclosure [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] 4.375% Senior Unsecured Notes Senior Notes [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt issued, face amount Debt Instrument, Face Amount Debt instrument, stated percentage Debt Instrument, Interest Rate, Stated Percentage Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of accumulated other comprehensive income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Segment Reporting Segment Reporting, Policy [Policy Text Block] Discontinued Operations Discontinued Operations, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Ground Leases Disclosures [Abstract] Ground Leases Disclosures [Abstract] 2019 (remainder of year) Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total minimum payments Lessee, Operating Lease, Liability, Payments, Due Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Amortization Ground Leases, Accumulated Amortization Deferred rent Deferred Rent Credit Right of use asset Leases, Operating [Abstract] Leases, Operating [Abstract] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Future minimum payments due Operating Leases, Future Minimum Payments Due Rent expense Operating Leases, Rent Expense, Net Operating Leases Receivable Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract] Remainder of 2019 Lessor, Operating Lease, Payments to be Received, Remainder of Fiscal Year 2020 Lessor, Operating Lease, Payments to be Received, Two Years 2021 Lessor, Operating Lease, Payments to be Received, Three Years 2022 Lessor, Operating Lease, Payments to be Received, Four Years 2023 Lessor, Operating Lease, Payments to be Received, Five Years 2024 Lessor, Operating Lease, Payments to be Received, Six Years Lessor, Operating Lease, Payments to be Received, Six Years Thereafter Lessor, Operating Lease, Payments to be Received, Thereafter Total Lessor, Operating Lease, Payments to be Received Assets by Segment [Abstract] Assets by Segment [Abstract] Assets New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Rental income - operating leases - continuing operations Rental Income, Operating Leases, Continuing Operations Rental Income, Operating Leases, Continuing Operations Rental income - operating leases - discontinued operations Rental Income, Operating Leases, Discontinued Operations Rental Income, Operating Leases, Discontinued Operations Variable lease income - operating leases - continuing operations Variable Lease Income, Operating Lease, Continuing Operations Variable Lease Income, Operating Lease, Continuing Operations Variable lease income - operating leases - discontinued operations Variable Lease Income, Operating Leases, Discontinued Operations Variable Lease Income, Operating Leases, Discontinued Operations Disclosure of Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Accumulated Other Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Real Estate Property, Plant and Equipment Disclosure [Text Block] Supplemental Cash Flow Information [Abstract] Supplemental Disclosure to Statements of Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Liberty Comcast 1701 JFK Boulevard, LP Liberty Comcast 1701 JFK Boulevard, LP [Member] Liberty Comcast 1701 JFK Boulevard, LP formerly known as Liberty Commerz 1701 JFK Boulevard, LP [Member] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Other Investments Other Investments [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Ownership interest in operating partnership - Limited Partnership Noncontrolling Interest, Ownership Percentage by Parent Equity investment in joint venture Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Discontinued Operations [Abstract] Discontinued Operations [Abstract] Discontinued operations Discontinued Operations [Member] Properties included in discontinued operations, held for sale Properties included in discontinued operations, sold Discontinued Operations, Disposed of by Sale [Member] Properties included in discontinued operations, total Properties included in continuing operations, held for sale Properties included in continuing operations, sold Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Properties included in continuing operations, total Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] Properties sold or classified as held for sale, held for sale Properties sold or classified as held for sale, sold Disposed of by Sale, Discontinued Operations and Not Discontinued Operations [Member] Assets disposed of during the year including discontinued and not discontinued operations. Properties sold or classified as held for sale, total Properties sold or classified as held for sale in the prior year and current year to date [Member] Properties sold or classified as held for sale in the prior year and current year to date [Member] Southeastern PA Southeastern PA [Member] Southeastern PA Discontined Operations Income Statement [Line Items] Capital expenditures Capital Expenditure, Discontinued Operations Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Revenues Disposal Group, Including Discontinued Operation, Revenue Operating expenses Disposal Group, Including Discontinued Operation, Operating Expense Depreciation and amortization Disposal Group, Including Discontinued Operation, Depreciation and Amortization Impairment expense Disposal Group, Including Discontinued Operation, Impairment Expense Amount of impairment expense attributable to disposal group, including, but not limited to, discontinued operation. Interest and other income Disposal Group, Including Discontinued Operation, Other Income (Loss) Disposal Group, Including Discontinued Operation, Other Income (Loss) Income taxes Interest expense Disposal Group, Including Discontinued Operation, Interest Expense Gain on property dispositions Income from discontinued operations Noncontrolling interest - operating partnership Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest Income from discontinued operations available to common shareholders Unit Repurchase [Abstract] Unit Repurchase [Abstract] Leaseholds and Leasehold Improvements Leaseholds and Leasehold Improvements [Member] Other Income Other Income [Member] Cambridge Medipark Ltd Cambridge Medipark Ltd [Member] Cambridge Medipark Ltd [Member] Gain on sale of leasehold interests Gain (Loss) on Sale of Investments Loss Contingencies [Table] Loss Contingencies [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] American Water Works, Inc American Water Works, Inc [Member] American Water Works, Inc [Member] Supply Commitment [Axis] Supply Commitment [Axis] Supply Commitment Arrangement [Domain] Supply Commitment Arrangement [Domain] Supply Commitment Supply Commitment [Member] Leasehold Improvements Leasehold Improvements [Member] Acres of developable land Equity Method Investments Equity Method Investments [Member] Category of Item Purchased [Axis] Category of Item Purchased [Axis] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment, Category of Item Purchased [Domain] Land Purchases Capital Addition Purchase Commitments [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Letters of credit outstanding Letters of Credit Outstanding, Amount Total anticipated development cost Development in progress Deferred leasing costs in development Deferred Costs, Leasing, Gross Remaining amount committed or obligated to pay Supply Commitment, Remaining Minimum Amount Committed Other commitment Other Commitment Remaining maximum amount committed for tenant improvements Supply Commitment, Remaining Maximum Amount Committed The ceiling amount as of the balance sheet date that the entity must expend to satisfy the terms of disclosed arrangements (excluding long-term commitments) in which the entity must commit resources to supply goods or services to one or more customers. Remaining amount committed to future acquisitions Purchase Commitment, Remaining Minimum Amount Committed AMOUNT UNITS LIQUIDATION PREFERENCE (in usd per share) Temporary Equity, Redemption Price Per Share DIVIDEND RATE Preferred Stock, Dividend Rate, Percentage Preferred units redeemed (in shares) Redeemable Noncontrolling Interest, Equity, Preferred, Shares Redeemed Redeemable Noncontrolling Interest, Equity, Preferred, Shares Redeemed Preferred units redeemed, value Redeemable Noncontrolling Interest, Equity, Preferred, Redemption Value Schedule of Preferred Units [Table] Preferred Units [Line Items] Limited Partners' Equity and Noncontrolling Interest of the Operating Partnership Statement of Stockholders' Equity [Abstract] Liberty Property Limited Partnership, Preferred Activity Liberty Property Limited Partnership, Preferred Activity [Member] Liberty Property Limited Partnership, Preferred Activity [Member] Equity Components [Axis] COMMON SHARES OF BENEFICIAL INTEREST Common Stock [Member] ADDITIONAL PAID-IN CAPITAL Additional Paid-in Capital [Member] ACCUMULATED OTHER COMPREHENSIVE LOSS DISTRIBUTIONS IN EXCESS OF NET INCOME Accumulated Distributions in Excess of Net Income [Member] TOTAL LIBERTY PROPERTY TRUST SHAREHOLDERS’ EQUITY Parent [Member] NONCONTROLLING INTEREST - OPERATING PARTNERSHIP Noncontrolling interest operating partnership Common [Member] Noncontrolling Interest Operating Partnership. NONCONTROLLING INTEREST - CONSOLIDATED JOINT VENTURES Noncontrolling interest-consolidated joint ventures [Member] Noncontrolling Interest Consolidated Joint Ventures. Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] GENERAL PARTNER General Partner [Member] LIMITED PARTNER Limited Partner [Member] TOTAL OWNERS’ EQUITY Noncontrolling interest operating partnership Preferred [Member] NonControlling Interest Operating Partnership Preferred. Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common shares outstanding - Beginning Balance (shares) General Partner's units outstanding - Beginning Balance (units) General Partners' Capital Account, Units Outstanding Limited Partners' units outstanding - Beginning Balance (units) Net proceeds from the issuance of common shares Stock Issued During Period, Value, New Issues Net proceeds from issuance of common shares (shares) Stock Issued During Period, Shares, New Issues Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Contributions from partners Partners' Capital Account, Contributions Contributions from partners (units) Partners' Capital Account, Units, Sale of Units Distributions to partners Partners' Capital Account, Distributions Distributions Dividends, Common Stock Share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Other comprehensive loss - foreign currency translation activity Other comprehensive income - derivative instruments activity Redemption of noncontrolling interest - preferred units Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Common shares outstanding - Ending Balance (shares) General Partner's units outstanding - Ending Balance (units) Limited Partners' units outstanding - Ending Balance (units) Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Noncontrolling Interest - Operating Partnership (Mezzanine) - Beginning Balance Net income (Mezzanine) Temporary Equity, Net Income Distributions Temporary Equity, Other Changes Noncontrolling Interest - Operating Partnership (Mezzanine) - Ending Balance Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Number of properties subject to ground lease (in properties) Number of Properties Subject to Ground Leases Weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Term of contract Lessee, Operating Lease, Term of Contract Renewal term Lessee, Operating Lease, Renewal Term Useful life increase interval Lessee, Operating Lease, Useful Life Increase Interval Lessee, Operating Lease, Useful Life Increase Interval Weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Leasing expense Operating Ground Lease Expense Operating Ground Lease Expense Cash portion of lease expense Lease, Cost, Cash Portion Lease, Cost, Cash Portion Schedule of supplemental disclosure to statement of cash flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Segment Information Segment Reporting Disclosure [Text Block] Schedule of fair value Fair Value, by Balance Sheet Grouping [Table Text Block] Other Significant Noncash Transactions [Table] Other Significant Noncash Transactions [Table] Operating Activities [Axis] Operating Activities [Axis] Operating Activities [Domain] Operating Activities [Domain] Continuing Operations Continuing Operations [Member] Other Significant Noncash Transactions [Line Items] Other Significant Noncash Transactions [Line Items] Write off of fully depreciated property and deferred costs Write off of fully depreciated property and deferred costs Write off of fully depreciated property and deferred costs Write of depreciated property and deferred costs due to sale/demolition Write Off Of Depreciated Property And Deferred Costs Due To Sale Write Off Of Depreciated Property And Deferred Costs Due To Sale Change in accrued development capital expenditures Change in accrued development capital expenditures The change in accrued expenses from prior period for development capital expenditures. Unrealized gain (loss) on cash flow hedge, non cash transaction Unrealized gain (loss) on cash flow hedge, non cash transaction Unrealized gain (loss) on cash flow hedge, non cash transaction Capitalized equity-based compensation Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Real Estate and Accumulated Depreciation, Location of Property [Axis] Real Estate and Accumulated Depreciation, Location of Property [Axis] Real Estate and Accumulated Depreciation, Location of Property [Axis] Real Estate and Accumulated Depreciation, Location of Property [Domain] Real Estate and Accumulated Depreciation, Location of Property [Domain] Real Estate and Accumulated Depreciation, Location of Property [Domain] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenue from improving land sites Revenue from remaining performance obligation Revenue, Remaining Performance Obligation, Amount